HP DC7800 - Manual (Page 109)

Serial Port
1. Prepare the computer for disassembly ( Preparation for Disassembly on page 60 ).
2. Remove the computer access panel ( Computer Access Panel on page 64 ).
3. Push down the green tabs (1), and then rotate the tab back 90 degrees out of the rear of the chassis
(2).
4. Disconnect the serial port cable from the system board (3).
5. Remove the port assembly from the chassis (4).
To install the serial port, reverse the removal procedure.
Serial Port 97